The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
With the development of mobile communication technology in recent times, mobile communication terminals are rapidly becoming popular. In addition, mobile communication systems gradually employ small cells, and there are continuous studies to ensure the quality of mobile communication services anytime and anywhere for the convenience of their subscribers.
Among the technologies for ensuring the quality of the mobile communication services, a distributed antenna system (DAS) operates to reduce the load of neighboring base stations by distributing data to a dedicated base station or low-load base stations.
FIG. 1 is an exemplary diagram of an analog distributed antenna system of the prior art.
As shown in FIG. 1, the conventional analog distributed antenna system is composed of a main unit (HE: Head-end) 100 and one or more remote units (RU: Remote Unit) 110-1 to 110-N. Meanwhile, the conventional analog distributed antenna system includes low-speed FSK modems, and transceives a control signal between the main unit 100 and the remote units 110-1 to 110-N by using the FSK modems. The FSK modem supports a data processing speed of 9.6 kbps. When the FSK modem is used, it takes about 104.2 ms to perform a control operation between the main unit 100 and the remote units 110-1 to 110-N.
A control signal transmission scheme using the low-speed FSK modem suffers from low efficiency in controlling multiple remote units at the same time. Furthermore, the conventional control signal transmission scheme might be able to serve multiple remote units at the same time while implementing such simple control functions as a status inquiry or state checking of the remote units at best, thereby failing to implement the important control functions such as context-based real-time control of the remote units and firmware download.